Bad news for alien life

It's a good point that actual communication with alien civilizations probably can't happen, but there could be fossil evidence of advanced civilization's footprints in the electromagnetic spectrum if they developed the capability of advanced communication and navigation technologies. Signals that we receive thousands of years after they were generated.
As interesting as it would be
to attempt to decipher inter-stellar communications
that were generated thousands of earth years ago,

I'm still getting nowhere trying to figure out my "smart phone."
 
It's a good point that actual communication with alien civilizations probably can't happen, but there could be fossil evidence of advanced civilization's footprints in the electromagnetic spectrum if they developed the capability of advanced communication and navigation technologies. Signals that we receive thousands of years after they were generated.
Agreed; fossil evidence is the best we can hope for due to the distances involved. As the NASA link below notes, there are about 1000 K dwarf stars like our own Sun within 100 LY.

Something interesting that's pertinent to our discussion is how our Sun is relatively short-lived. In a billion years, the Sun will have swelled to the point of beginning to desiccate the Earth. Not that we'll care at that point, but if another star like ours but a billion years older had an advanced civilization, their home planet would become uninhabitable. This could be a factor in reducing the number of advanced civilizations that are observable within 100 LY.

For starters, there are three times as many K dwarfs in our galaxy as stars like our Sun. Roughly 1,000 K stars lie within 100 light-years of our Sun as prime candidates for exploration. These so-called orange dwarfs live from 15 billion to 45 billion years. By contrast, our Sun, now already halfway through its lifetime, lasts for only 10 billion years. Its comparatively rapid rate of stellar evolution will leave the Earth largely uninhabitable in just another 1 or 2 billion years. "Solar-type stars limit how long a planet's atmosphere can remain stable," Guinan said. That's because a billion or so years from now, Earth will orbit inside the hotter (inner) edge of the Sun's habitable zone, which moves outward as the Sun grows warmer and brighter. As a result, the Earth will be desiccated as it loses its present atmosphere and oceans. By an age of 9 billion years the Sun will have swelled up to become a red giant that could engulf the Earth.
 
Agreed; fossil evidence is the best we can hope for due to the distances involved. As the NASA link below notes, there are about 1000 K dwarf stars like our own Sun within 100 LY.

Something interesting that's pertinent to our discussion is how our Sun is relatively short-lived. In a billion years, the Sun will have swelled to the point of beginning to desiccate the Earth. Not that we'll care at that point, but if another star like ours but a billion years older had an advanced civilization, their home planet would become uninhabitable. This could be a factor in reducing the number of advanced civilizations that are observable within 100 LY.

For starters, there are three times as many K dwarfs in our galaxy as stars like our Sun. Roughly 1,000 K stars lie within 100 light-years of our Sun as prime candidates for exploration. These so-called orange dwarfs live from 15 billion to 45 billion years. By contrast, our Sun, now already halfway through its lifetime, lasts for only 10 billion years. Its comparatively rapid rate of stellar evolution will leave the Earth largely uninhabitable in just another 1 or 2 billion years. "Solar-type stars limit how long a planet's atmosphere can remain stable," Guinan said. That's because a billion or so years from now, Earth will orbit inside the hotter (inner) edge of the Sun's habitable zone, which moves outward as the Sun grows warmer and brighter. As a result, the Earth will be desiccated as it loses its present atmosphere and oceans. By an age of 9 billion years the Sun will have swelled up to become a red giant that could engulf the Earth.
Good info.

I really wonder if the lifespan of our species is really going to be more than a few hundred thousand years. We are defying the laws of evolution by allowing the stupid, the MAGA, the weak, the infirm to exist and breed. Not that it's wrong to do so, but it deviates from the laws of evolution. We are already seeing that human brains are getting smaller than they were in Paleolithic humans. We have diseases and genetic mutations that never existed in the Paleolithic era.

Perhaps we will devolve into a species of dimwitted troglodytes - I offer to you Trump rallies as one line of evidence of where we're heading!
 
As interesting as it would be
to attempt to decipher inter-stellar communications
that were generated thousands of earth years ago,

I'm still getting nowhere trying to figure out my "smart phone."
Math and science is often thought to be a literal Universal language. A hydrogen atom on Earth would be the same as a hydrogen atom on the other side of our galaxy. The measurements and physics involved would be the same regardless of their numbering system.

NASA scientists understood this when they designed the Pioneer 10 plaque and included a diagram of a hydrogen atom in a state of transition.

maxresdefault.jpg


The Pioneer Plaque: Science as a Universal Language​

20160116_pioneer-plaque.jpg.webp
 
Good info.

I really wonder if the lifespan of our species is really going to be more than a few hundred thousand years. We are defying the laws of evolution by allowing the stupid, the MAGA, the weak, the infirm to exist and breed. Not that it's wrong to do so, but it deviates from the laws of evolution. We are already seeing that human brains are getting smaller than they were in Paleolithic humans. We have diseases and genetic mutations that never existed in the Paleolithic era.

Perhaps we will devolve into a species of dimwitted troglodytes - I offer to you Trump rallies as one line of evidence of where we're heading!
Possible. Per Fermi's Paradox, one reason there might not be many advanced civilizations is because they destroy themselves.

Trump rallies are, indeed, a good example of both dimwits and throwbacks. LOL
 
Math and science is often thought to be a literal Universal language. A hydrogen atom on Earth would be the same as a hydrogen atom on the other side of our galaxy. The measurements and physics involved would be the same regardless of their numbering system.

NASA scientists understood this when they designed the Pioneer 10 plaque and included a diagram of a hydrogen atom in a state of transition.

maxresdefault.jpg


The Pioneer Plaque: Science as a Universal Language​

20160116_pioneer-plaque.jpg.webp
Advanced aliens would be probably able to decifer signals incorporating prime numbers, the Fibonacci sequence, geometric relationships.
 
Advanced aliens would be probably able to decifer signals incorporating prime numbers, the Fibonacci sequence, geometric relationships.
Agreed. The math and laws of the Universe would be the same across the galaxy.

Well, maybe not inside the Great Black Hole at the core, but across all habitable planets. LOL
 
Well, it should be rational and fairly easy to postulate that an advanced society might not produce the same technology that we've produced. There are clearly multiple paths a species could take to get advanced. For example, some alien civilization lives on a planet with the upper atmosphere being highly ionized, so they never produce the sort of high-power radio signals we do. They aren't listening and they aren't sending. They might even have colonized other planets in their own system and simply gone to lasers to avoid the problem for communications between them.

Or, an alien civilization evolved to communicate using visual means only and has limited itself to face-to-face communications. It might not ever develop radio and other electromagnetic communications devices so no signals would be detected by them or sent from them, yet they could be on par with us in many other areas.

There's just too many variables here to know for sure and our database on this is essentially nil.
 
Well, it should be rational and fairly easy to postulate that an advanced society might not produce the same technology that we've produced. There are clearly multiple paths a species could take to get advanced. For example, some alien civilization lives on a planet with the upper atmosphere being highly ionized, so they never produce the sort of high-power radio signals we do. They aren't listening and they aren't sending. They might even have colonized other planets in their own system and simply gone to lasers to avoid the problem for communications between them.

Or, an alien civilization evolved to communicate using visual means only and has limited itself to face-to-face communications. It might not ever develop radio and other electromagnetic communications devices so no signals would be detected by them or sent from them, yet they could be on par with us in many other areas.

There's just too many variables here to know for sure and our database on this is essentially nil.
Lasers use photons and are thus are themselves utilizing electromagnetic radiation.

EM radiation is such a fundamental and ubiquitous foundation of all physical reality, it's hard to believe that no other alien civilization would figure out how to use it for communication and navigation. The reason we are only scanning the radio and microwave frequencies for artificial transmissions is because only long wavelength radiation can travel long distances.
 
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Lasers use photons and are thus are themselves utilizing electromagnetic radiation.

EM radiation is such a fundamental and ubiquitous foundation of all physical reality, it's hard to believe that no other alien civilization would figure out how to use it for communication and navigation. The reason we are only scanning the radio and microwave frequencies for artificial signals is because only long wavelength radiation can travel long distances.
It isn't a matter of figuring it out, it's a matter of needing it for some reason. My point is that an alien society might decide there's no value or use in it--and our standards on that don't apply here. There are ways to navigate and communicate besides using electromagnetic means.

What works for us, might not work for them.

For example, the heliograph.

Aparato-heli%C3%B3grafo.jpg


Maybe they are visual and communicate visually, not by audio. For such a species, radio makes zero sense. So, instead, they invent means to communicate over long distances using light and their means are not something we could detect at distances of hundreds to thousands of light years.
 
It isn't a matter of figuring it out, it's a matter of needing it for some reason. My point is that an alien society might decide there's no value or use in it--and our standards on that don't apply here. There are ways to navigate and communicate besides using electromagnetic means.

What works for us, might not work for them.

For example, the heliograph.

Aparato-heli%C3%B3grafo.jpg


Maybe they are visual and communicate visually, not by audio. For such a species, radio makes zero sense. So, instead, they invent means to communicate over long distances using light and their means are not something we could detect at distances of hundreds to thousands of light years.

There aren't only two possibilities:
1) Aliens will use the EM spectrum.
2) Aliens will not use the EM spectrum.

The balance of probability is that at least some advanced alien civilizations will leave a footprint in the EM spectrum similar to the way we are.
 
There aren't only two possibilities:
1) Aliens will use the EM spectrum.
2) Aliens will not use the EM spectrum.

The balance of probability is that at least some advanced alien civilizations will leave a footprint in the EM spectrum similar to the way we are.
It's more complex than that.

3. Aliens will use some part of the EM spectrum
4. Aliens use only a part of the EM spectrum we cannot detect at great distances
5. Coherent, intelligent, EM signals are undetectable at great distances

We don't have enough data to know for sure at this point.
 
It's more complex than that.

3. Aliens will use some part of the EM spectrum
4. Aliens use only a part of the EM spectrum we cannot detect at great distances
5. Coherent, intelligent, EM signals are undetectable at great distances

We don't have enough data to know for sure at this point.
I agree that SETI and other attempts to detect artificial signals have only examined a tiny part of the galaxy, and it's like finding a needle in a haystack.

The WOW signal detected in 1977 at the Ohio State University radio telescope has never been adequately explained, and if nothing else seems to show we had the capability 50 years ago to detect anomalous radio frequency signals from star systems hundreds of light years away - I assume our technical capabilities in this area have improved in the half century since 1977.
 
The 'habitable' zone in the Milky Way galaxy is a thin ring about 25k to 33k light years from the Galactic center, which is where our sun is. The Milky Way is 100k light years in diameter, so the Galactic habitable zone is only seven percent of the galactic volume and only 5 percent of the galaxy's stars.

Conclusion - If there there are 100 billion stars in the Milky Way, only 5 billion of them are even possibly suitable for life. And then you have to start thinking about all the other perfect storm conditions that allowed advanced life to evolve on Earth.

Star systems near the densely packed galactic core are too frequently bathed in life-sterilizing gamma ray bursts from supernovas and colliding neutron stars for biological evolution to flourish.

Stars out on the galactic rim are starved of heavy elements necessary for life because the stars are too spread out and there are too few supernova.
 
The 'habitable' zone in the Milky Way galaxy is a thin ring about 25k to 33k light years from the Galactic center, which is where our sun is. The Milky Way is 100k light years in diameter, so the Galactic habitable zone is only seven percent of the galactic volume and only 5 percent of the galaxy's stars.

Conclusion - If there there are 100 billion stars in the Milky Way, only 5 billion of them are even possibly suitable for life. And then you have to start thinking about all the other perfect storm conditions that allowed advanced life to evolve on Earth.

Star systems near the densely packed galactic core are too frequently bathed in life-sterilizing gamma ray bursts from supernovas and colliding neutron stars for biological evolution to flourish.

Stars out on the galactic rim are starved of heavy elements necessary for life because the stars are too spread out and there are too few supernova.
I forgot to point out that of those five billion stars in the galactic habitable zone, at least 80 percent of them are M class red dwarfs, or gas giants. So you are really only talking about one billion stars in the galaxy that could even possibly have the potential for life, and that's before you start looking for the perfect storm conditions that Earth had
 
The 'habitable' zone in the Milky Way galaxy is a thin ring about 25k to 33k light years from the Galactic center, which is where our sun is. The Milky Way is 100k light years in diameter, so the Galactic habitable zone is only seven percent of the galactic volume and only 5 percent of the galaxy's stars.

Conclusion - If there there are 100 billion stars in the Milky Way, only 5 billion of them are even possibly suitable for life. And then you have to start thinking about all the other perfect storm conditions that allowed advanced life to evolve on Earth.

Star systems near the densely packed galactic core are too frequently bathed in life-sterilizing gamma ray bursts from supernovas and colliding neutron stars for biological evolution to flourish.

Stars out on the galactic rim are starved of heavy elements necessary for life because the stars are too spread out and there are too few supernova.
Excellent analysis.

Is the 5B number accounting for the 70% that are M class red dwarfs? If so, even at 1-in-a-million odds for a perfect storm, that allows 5000 star systems with life. Even whacking half of them from natural occurrences and half of those from self-eradication would leave over a 1000 human-level or greater advanced life forms.

That said, the laws of physics still apply. Without a deus ex machina type technology like "warp drive" or Heinlein's teleportation "Ramsbotham jump" described in "Tunnel in the Sky", I fail to see how these various civilizations can communicate, much less physically contact each other. They could become aware of each other, but traveling from point A to point B would be highly problematic even with the use of multi-generation colony ships as described in Arthur C. Clarke's "Rendezvous with Rama" or Heinlein's "Orphan's in the Sky" since they are one-way trips.


 
I forgot to point out that of those five billion stars in the galactic habitable zone, at least 80 percent of them are M class red dwarfs, or gas giants. So you are really only talking about one billion stars in the galaxy that could even possibly have the potential for life, and that's before you start looking for the perfect storm conditions that Earth had
One-in-a-million "perfect storms" drops the number to 1000 stars. Again, wipe out half by natural occurrences and half of that from self-induced extinction/civilization destroying disasters would still leave 250 advanced civilizations.
 
One-in-a-million "perfect storms" drops the number to 1000 stars. Again, wipe out half by natural occurrences and half of that from self-induced extinction/civilization destroying disasters would still leave 250 advanced civilizations.
Nice.

And that is assuming a long series of improbable events over four billion years that led to the unique emergence of Homo Sapiens.

The fact that life was perfectly happy on Earth for 3 billion years as single celled microbes before making a sudden and abrupt jump to multicellular complex life, suggests life might be perfectly happy to exist as just microbes for billions of years
 
Excellent analysis.

Is the 5B number accounting for the 70% that are M class red dwarfs? If so, even at 1-in-a-million odds for a perfect storm, that allows 5000 star systems with life. Even whacking half of them from natural occurrences and half of those from self-eradication would leave over a 1000 human-level or greater advanced life forms.

That said, the laws of physics still apply. Without a deus ex machina type technology like "warp drive" or Heinlein's teleportation "Ramsbotham jump" described in "Tunnel in the Sky", I fail to see how these various civilizations can communicate, much less physically contact each other. They could become aware of each other, but traveling from point A to point B would be highly problematic even with the use of multi-generation colony ships as described in Arthur C. Clarke's "Rendezvous with Rama" or Heinlein's "Orphan's in the Sky" since they are one-way trips.


Agree.

I think Star Trek, and the misuse of the Drake Equation in the 1970s primed us to believe that our galaxy would be pregnant with millions of planets with advanced life.

Agree that the laws of physics probably preclude any tangible probability of communication and travel between civilizations
 
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